Wednesday, February 18, 1998 Published at 14:36 GMTSci/TechVoyager hurtles deep into outer spaceVoyager pictured against the planet, Neptune

A US spacecraft, carrying evidence of intelligent life on Earth, has become the most distant human-made object in the universe.

Since its launch 20 years ago, Voyager 1 has hurtled more than 10 billion kilometres (6.5 billion miles) into space, surpassing the distance of the older Pioneer 10 spacecraft.

"Now the baton is being passed," said Edward Stone, the director of Nasa's Jet Propulsion Laboratory and Voyager project director.

Voyager 1 and the elderly Pioneer 10 are heading away from the Sun in nearly opposite directions.

Both are powered by nuclear batteries that keep them functioning in the freezing blackness of space.

Signals take hours to reach earth

On the edge of the solar system, Voyager 1 still returns data, although the power of the signal reaching Nasa antennas is 20 billion times weaker than the power of a digital watch battery.

Travelling at the speed of light, signals from Voyager take nearly 10 hours to reach Earth.

The Voyager 1 spacecraft

Voyager 1 was launched from Cape Canaveral, Florida, on September 5, 1977, carrying scientific instruments for planetary exploration and a message to the universe.

The message is contained on a 30-centimetre (12-inch) gold-plated phonograph record. It contains a variety of sounds, 115 images, spoken greetings in 55 languages, printed messages from former President Jimmy Carter and then UN Secretary General, Kurt Waldheim, and a selection of music.

A mother's kiss

The sounds include wind, rain, surf, a chimpanzee, a Saturn 5 rocket, footsteps, a heartbeat, laughter, and a mother's kiss.

The images range from the structure of DNA to a diagram of continental drift and a violin with sheet music.

Carl Sagan helped choose the objects on Voyager

The record was assembled by a committee that was headed by the late astronomer, Carl Sagan.

Voyager 1 passed by Jupiter on March 5, 1979 and Saturn on November 12, 1980.

Saturn's big moon, Titan, bent the trajectory northward out of the plane of the ecliptic - the plane in which all the planets except Pluto orbit the sun.

Pioneer 10 was launched on March 2, 1972. Its mission officially ended on March 31, 1997, but science data is occasionally sent to Earth in a training program for flight controllers.

Barring breakdowns, Voyager I is expected to have enough electricity and propellant to operate until about 2020.

By then, the spacecraft will be almost 22.5 billion kilometres (14 billion miles) from Earth.